fn main() {
    let input = advent::read_lines(5);
    println!("5a: {}", count_nice(&input, is_nice));
    println!("5b: {}", count_nice(&input, is_nice2));
}

fn is_nice(word: &str) -> bool {
    let mut prev = ' ';
    let mut vowel_count = 0;
    let mut double_letter = false;

    for c in word.chars() {
        if ['a', 'e', 'i', 'o', 'u'].contains(&c) {
            vowel_count += 1;
        }
        if prev == c {
            double_letter = true;
        }
        let pair = format!("{}{}", prev, c);
        if ["ab".to_string(), "cd".to_string(), "pq".to_string(), "xy".to_string()].contains(&pair) {
            return false;
        }

        prev = c;
    }
    double_letter && vowel_count >= 3
}

fn has_two_pairs(word: &str) -> bool {
    let mut prev = ' ';

    for c in word.chars() {
        let pair = format!("{}{}", prev, c);

        if word.matches(&pair).count() > 1 {
            return true;
        }

        prev = c;
    }
    false
}

fn has_one_letter_repeat(word: &str) -> bool {
    let mut prev = ' ';
    let mut prevprev = ' ';

    for c in word.chars() {
        if c == prevprev {
            return true;
        }
        prevprev = prev;
        prev = c;
    }
    false
}

fn is_nice2(word: &str) -> bool {
    has_two_pairs(word) && has_one_letter_repeat(word)
}

fn count_nice(input: &[String], f: fn(&str) -> bool) -> usize {
    input.iter()
         .filter(|&x| f(x))
         .count()
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test() {
        assert!(is_nice("ugknbfddgicrmopn"));
        assert!(is_nice("aaa"));
        assert!(!is_nice("jchzalrnumimnmhp"));
        assert!(!is_nice("haegwjzuvuyypxyu"));
        assert!(!is_nice("dvszwmarrgswjxmb"));

        assert!(is_nice2("qjhvhtzxzqqjkmpb"));
        assert!(is_nice2("xxyxx"));
        assert!(!is_nice2("uurcxstgmygtbstg"));
        assert!(!is_nice2("ieodomkazucvgmuy"));
    }
}